Blow guns

ABSTRACT

Gun for a jet of fluid under pressure of the type of blow-guns and the like, characterized in that it comprises a pressure regulator directly incorporated therein.

United States Patent Geoffray May 20, 1975 [54] BLOW GUNS 2,844,408 7/1958 Dickmann et a1 239/526 X 3,394,890 7/1968 Heinrich et a1. 239/526 [761 Inventor? Gwflray Rue 3,612,406 10/1971 Bass et a1 239/526 Jeanne dArc, Lyon, France 22 i J 17 1973 FOREIGN PATENTS OR APPLICATIONS Appl. NO.Z 380,120

Foreign Application Priority Data July 19, 1972 France 72.26781 U.S. Cl 239/526; 239/569 Int. Cl BOSb 7/02; 1305b l/30 Field of Search 239/464, 525, 526, 533,

References Cited UNITED STATES PATENTS 7/1952 Yates 239/572 X 207,725 5/1957 Australia 239/572 Primary ExaminerR0bert S. Ward, Jr. Attorney, Agent, or Firm-Dowell & Dowel] [57] ABSTRACT 3 Claims, 3 Drawing Figures MTENTEU mm M 5 mm c a b 3 A 8 Z 2 rm BLOW GUNS DESCRIPTION OF THE INVENTION The present invention relates to guns intended for producing jets of fluid under pressure and in particular of compressed air, which are currently known by the name blow-guns".

The compressed air pressure available for supplying apparatus of the type in question is generally too high for obtaining thedesired jet of air. Thus. it is necessary either to provide a special feed apparatus, for example with. a pressure regulator interposed between the source of compressed air and the pipes to which the blow-gunsare connected, or to provide each apparatus with a device producing a pressure drop through a cali bratedaperture or the like. The first solution complicates the apparatus in the workshops concerned, whilst the second gives only imperfect results, a device having a pressure drop being able to ensure a predetermined outlet pressure solely for precise values of the upstream pressure and of the rate of flow.

The invention intends to remedy the preceding drawbacks andto provide a blow-gun which is able to produce a jet of compressed air or other fluid under pressure which in practice depends neither on the rate of flow, nor on the pressure in the pipe supplying the apparatus.

The gun or blow-gun according to the invention is characterised in that it comprises a pressure regulator incorporated directly therein.

The pressure regulator may comprise an elastically deformable membrane attached to a valve co-operating with a fixed seat, said membrane being subjected, on the one hand, on one side to the downstream pressure, on the other hand, on its opposite side to the combined action of atmospheric pressure and of a calibrated spring bearing against a plate or movable control member. Nevertheless, according to a particularly advantageous embodiment, the pressure sensitive member associated with the calibrated spring is constituted by a tubular piston provided with a seat for the closure valve, which valve is in turn connected to a control member.

The pressure regulator is preferably combined with the lever or trigger actuating system of the gun such that it is possible for the operator to regulate the effective pressure of the jet by actuating the customary lever or trigger which thus forms the above-said control member.

The accompanying drawing illustrates one embodiment of the invention as an example.

FIG. I is a general axial section of the gun.

FIG. 2 shows in perspective, the inner end of one of the two parts forming the body of this gun.

FIG. 3 is a cross-section on line IIllIl (FIG. 1).

The body of the gun illustrated in FIG. 1 is constituted by two parts 1 and 2 of circular section, connected by screwing at 3 so that they are air-tight. The part 1 comprises an axial bore la whose ends open respectively into an inner chamber 2a of the part 2 and into a central aperture 119 of the part 1; the walls of the aperture lb define a type of clevis inside which is engaged the heel 4a of an operating lever or trigger 4 pivoted at 5. The heel 40 has a shape such that when it is tilted, it ensures the axial control of a cylindrical pushrod 6 slidably engaged in the bore 1a in an air-tight manner; it will be noted that the push-rod 6 is integral with a tubular shank 6a whose inner space is connected to a channel 6b provided in said push-rod and opening into the aperture 1b.

The tubular shank 6a of the push-rod 6 is engaged with considerable annular clearance inside a piston 7 which is also tubular; two gaskets 8 ensure the seal of the piston 7 sliding inside a part or cup 9 which is kept axially stationary in the chamber 20, said piston being urged in the direction of the aperture lb by a calibrated spring 10. It will be noted that the lateral wall of the cup 9 is provided with an aperture 9a located opposite a groove 2b providedin the chamber 2a, which groove opens externally to facilitate the free sliding of the piston 7. I

Towards the rear, the chamber 2a is connected to a second chamber 20 of smaller diameter, inside which is mounted a valve 11 of square section (FIG. 3). This valve 11 comprises a metal sleeve in which is retained a seal intended to bear against the free end or seat of the piston 7 under the action of a spring 12. The chamber 20 is connected by a filter 13 to the inner space of a connection 14 facilitating the attachment of a flexible pipe 15 supplied with air under pressure.

On each side of the opening of the bore 1a, the part 1 is provided with a notch 10 (FIG. 2) into which opens one of the two longitudinal channels la which extend forwards on either side of the axial bore la and central aperture 1b in order to ensure the connection of the chamber 2a to the front end of said part 1, Screwed into the latter is a nozzle or nose-piece 16 comprising an axial mouth-piece 16a for the discharge of compressed air passing through the two channels 1d.

The operation of the above described apparatus will be readily understood. In the stationary (closure) position of the lever 4, the valve lll is retained against the end of the tubular piston 7 and thus opposes any escape of compressed air. When the lever 4 is opened by tilting, the push rod 6 is displaced axially and the shank 6a pushes the valve 11 against the action of the spring 12; compressed air passes around the valve 11 and pene trates inside the piston 7 to escape partially through the notches 1c, the channels In and the mouth-piece 16a. It will be noted that the valve 11 is pressed against the tubular shank 6a of the push-rod 6 and thus opposes any escape through the channel 6b.

The high pressure compressed air thus fills the space in the chamber 2a comprised between the end of the part 1 and the piston 7 such that the latter moves back against the action of its spring 10 and thus moves towards the valve 11, reducing the free section for the flow between the seat and the valve. In this way, equilibrium is achieved which finally depends solely on the position of the push-rod 6, i.e. on the movement of the lever 4. A screw 17 engaged in this lever 4 makes it possible to regulate the end of stroke position of said lever, i.e. the maximum pressure prevailing in the mouthpiece 16a. It will be understood that this maximum pressure is independent of the rate of flow and consequently of the section of the nozzles or nose-pieces 16 which the apparatus may comprise; it is retained when the outlet of the latter is blocked and it in no way depends on the upstream pressure such that it is in no way affected by variations of the latter.

In the case of accidental excess pressure in the mouth-piece 16a, the pressure-sensitive member constituted by the piston 7 moves beyond the normal position for closing the valve 11 such that the end of the tubular shank 6a of the push-rod 6 is uncovered to ensure decompression in said mouth-piece.

Naturally, the lever 4 may be controlled cyclically by means of a cam or similar member. The body of the apparatus may be shaped in the manner of a gun, the lever 4 having the shape of a real trigger. Finally, it will be understood that in certain cases, this lever or trigger may be replaced by a simple adjustable screw acting on the push-rod 6, the control of the emission of the jet thus being directly placed under the dependence of the supply of the pipe 15.

I claim:

l. A blow gunfor delivering a jet of compressed air from an air inlet through a nozzle, comprising:

a body supporting said nozzle at its front end and having at its rearend said compressed air inlet, and the. body having a central portion including a first chamber 7 communicating at its forward end through channel means with said nozzle, and the body furtherincluding a second chamber behind the first chamber and communicating with said air inlet, thechambers being axially aligned and joined by a passage;

a hollow piston member axially slidable in sealing engagement in the first chamber and extending through said-passage into said second chamber, the piston having an opening therethrough and having a rearwardly facing valve seat in the opening;

. a valveoverlying the rearwardly facing seat;

spring means yieldably urging the valve against the seat;

a calibrated spring in the first chamber and yieldably urging said piston forwardly therein toward the nozzle;

a push rod in the opening of the hollow piston and operative when displaced rearwardly to raise the valve off of the seat; and

manually operated means carried by the body and operative when actuated to displace the push rod rearwardly to displace the valve, whereby air under pressure passes through the hollow piston into the first chamber forward of the piston and displaces the piston rearwardly to modulate the valve opening when the force of the air pressure on the piston exceeds the force of the calibrated spring, thereby to regulate the pressure of the air delivered to the nozzle.

2. The blow gun according to claim 1, wherein said push rod has an axial bore extending therethrough and opening at its rear end toward said valve, and the axial bore communicating with an externally opening channel, whereby when the push rod is out of contact with the valve the pressure within said central portion of the body is vented.

3. The blow gun as set forth in claim 2, wherein said body has a forward portion connecting said nozzle with said central portion, the forward portion including a transverse aperture and including a central bore slidably receiving said push rod, and said manually operated means comprising a lever pivotally mounted in said forward portion and contacting the forward end of said push rod, and said forward portion having channels laterally offset from said central bore and which connect the forward end of said first chamber with said nozzle. 

1. A blow gun for delivering a jet of compressed air from an air inlet through a nozzle, comprising: a body supporting said nozzle at its front end and having at its rear end said compressed air inlet, and the body having a central portion including a first chamber communicating at its forward end through channel means with said nozzle, and the body further including a second chamber behind the first chamber and communicating with said air inlet, the chambers being axially aligned and joined by a passage; a hollow piston member axially slidable in sealing engagement in the first chamber and extending through said passage into said second chamber, the piston having an opening therethrough and having a rearwardly facing valve seat in the opening; a valve overlying the rearwardly facing seat; spring means yieldably urging the valve against the seat; a calibrated spring in the first chamber and yieldably urging said piston forwardly therein toward the nozzle; a push rod in the opening of the hollow piston and operative when displaced rearwardly to raise the valve off of the seat; and manually operated means carried by the body and operative when actuated to displace the push rod rearwardly to displace the valve, whereby air under pressure passes through the hollow piston into the first chamber forward of the piston and displaces the piston rearwardly to modulate the valve opening when the force of the air pressure on the piston exceeds the force of the calibrated spring, thereby to regulate the pressure of the air delivered to the nozzle.
 2. The blow gun according to claim 1, wherein said push rod has an axial bore extending therethrough and opening at its rear end toward said valve, and the axial bore communicating with an externally opening channel, whereby when the push rod is out of contact with the valve the pressure within said central portion of the body is vented.
 3. The blow gun as set forth in claim 2, wherein said body has a forward portion connecting said nozzle with said central portion, the forward portion including a transverse aperture and including a central bore slidably receiving said push rod, and said manually operated means comprising a lever pivotally mounted in said forward portion and contacting the forward end of said push rod, and said forward portion having channels laterally offset from said central bore and which connect the forward end of said first chamber with said nozzle. 